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Summary:
"Bigger Than Ever: The U.S. National Electrical Code
(NEC)" With
trilingual summary
What
electrical installation practices can be permitted only in a
"supervised industrial installation"? The definition of such an
environment has remained tucked away in certain NEC sections, of
which 240.2 is one, and is associated with one of the Code's more
significant long-running controversies.
Debate
began years ago over the basic nature of the NEC. The argument grew
especially heated with the growth of large petrochemical industries
in which electric power apparatus and circuitry were essential to
round-the-clock process operation. Cable tray, direct burial, and
operating voltages as high as 14,400 were far outside the typical
electrician's concern for 120 volt residential wiring, or conduit
installation in commercial buildings.
Whereas the
typical residential or commercial electrical system, is used by
individuals untrained in electrical technology, or equipped to
supervise, maintain, or repair apparatus or circuits, the large
industrial facility normally has an operating and maintenance staff
knowledgeable in such matters.
Engineering
groups therefore began arguing for a separate "industrial" code,
slanted towards the differing needs of installations in
manufacturing facilities, that would enable them to use their
expertise to assure safety without applying many NEC provisions that
suited only premises occupied by untrained citizens.
Although
the movement to establish an entirely separate code has never borne
fruit, today's NEC does contain many notes, exceptions, and
references to permit or suggest practices outside the norms in
situations where electrical systems and apparatus are "installed and
maintained in industrial settings by trained workers." Similarly,
certain practices not normally permitted by the NEC may be allowable
"under engineering supervision" (see, for example, Exception No. 4
to Section 310.4). One of the more detailed exceptions appears in
Section 314.50 concerning electric enclosures intended for personnel
entry: "Where electric enclosures...are part of an industrial wiring
system operating under conditions of maintenance and supervision
that ensure only qualified persons monitor and supervise the system,
they shall be permitted to be designed and installed in accordance
with appropriate engineering practice..."
So -- "Why
not an industrial electrical code?" asked one headline decades ago.
Process industries in Canada, where many large petrochemical
projects are under development, have begun to act on that question.
With the aid of the Canadian Standards Association, such users
launched the "OBIEC" project late in 2003. The acronym stands for
"Objective Based Industrial Electrical Code."
The
document is in the initial drafting stage, with completion scheduled
for the end of 2005. It will be based on defined objectives of
operating safety, leaving many of the detailed requirements
("prescribed" by existing codes) up to the system or project
designer. The major references will be IEEE standards.
Only
"qualified" (as determined by regulatory agencies in each Canadian
province) industrial firms will be allowed to use the OBIEC
procedures. Regular audits will be required for maintaining that
qualification. An accompanying "safety management system" will
establish the regulatory capability.
Much work
remains to be done. Will such an alternative code someday be adopted
in the United States? That appears unlikely, but firm predictions
may be unwise.
From
"Bigger Than Ever: The U.S. National Electrical Code (NEC)"
...by
Richard L. Nailen, EA Engineering Editor - published in Electrical Apparatus January 2005
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Barks Publications, Inc. All Rights Reserved.
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